Blisters in Nickel Plating with temperature
A discussion started in 2005 & continuing through 2017
Q. We have a problem that we hope someone can help us, we are a job shop plater and we are Nickel plating Zamac (Zinc Die Casts) parts that have a good die condition. Parts are processed in racks and mainly they are a plate 1/8" Thick approx.
The problem is our client welds in a reflux oven the parts and they go up to 225 °C (437 °F) for 4 minutes. The initial samples 160 pieces where perfect, the we sent 1400 and 5.7% had problems with blisters, then we sent another 3800 parts, and out of 100 samples, 24% had blisters after the reflux welding.
our Process is:
Degreaser in process for Zamac, 60 gr/lt and 60 °C Rinses
Activate with Acid Salt 30 grms/lt temp. ambient
Alkaline Copper 10 minutes 60 °C
Activate in Sulfuric Acid 5% amb temp
Please any feed back will be very good. We haven't received the parts to examine them for the blistering, to see if it comes from the base metal or the copper.
Thanks for your helpSergio Hernandez
Plating job shop - Guadalajara, Jalisco, México
A. 10 minutes copper plating sounds too little. I would try a heavier copper plate first. The acids may be attacking the Zamac, and causing poor adhesion which results in blisters later.
Jeffrey Holmes, CEF
A. The problem is probably one of two things
These would be the most common if the blister is copper from the die cast. It would be necessary to look at the back of the blister to determine what exactly is blistering.Gene Packman
process supplier - Great Neck, New York
A. Looks like liquids got entrapped under the plate. Subsequent exposure to high temperature made them expand or boil. So, my suggestion would be to inspect for pores or cracks before processing. Also, it may be beneficial to add an electrocleaning step after the degreaser.Guillermo Marrufo
Monterrey, NL, Mexico
Are the blisters peeling off down to the substrate (zinc) or is the nickel peeling and leaving copper? Other than the heat, my process is very similar to your (I use a copper cyanide bath...is this what you mean by alkaline copper?). I've never experienced this problem if the line specs are OK unless I had some very porous castings.
A. Guadalejara ! Blister problem after copper plate, 1) peel the blister then check the on die cast if it is black spot,make sure activation good, check the concentration of your acid salt tank and dumping and make up new schedule. check the copper strike for any other contamination like chrome, analyze the copper strike for detail contamination.
Thank you for all your responses.
I did what was suggested and peeled the blister, we found a greyish color in both parts of the blister. Photo included. There is no Copper in sight and the color is grey, as the die cast. Not black as if with smut.
Gene, if the problem is not copper from the die cast, what should we do?
Guillermo, in reality the bubbles only appear after the high temperature. There are no pores visible in the die cast.
Trent, the blisters are peeling off down from the substrate, see photo. what can we do?
Yes our alkaline Copper is a copper cyanide bath, (it's not a strike)
Can you help me with the lone specs for his work?
Thanks again to all for your time and help.Sergio Hernandez [returning]
- Guadalajara, Jalisco, Mexico
A. Based on your opinion, because the photo is not clear enough, it seems that the zinc delaminated from itself. This could be attributed to inadequate casting practice more than a plating error. In such a case, it would be interesting for you to expose some unplated parts to the high temperature and see if they tolerate it without damage.Guillermo Marrufo
Monterrey, NL, Mexico
It seems your pretreatment is very poor. If I were you, I would use electrolytic degrease. I mean, your parts exposed to high temperature and your parts occurred gas bubbles (H2). This bubbles occur after plating as a blisters. So, If you use electrolytic degreasing (either before cathodic and later anodic) after hot degreasing, you will solve this problem. But it must either cathodic and anodic. This is very important. Because anodic will remove gas bubbles. Try these, and reply to me please ...
Good Luck...Emre Tuna
Please check that the casting is not laminated. If it is cast in the Hot Chamber process the castings should be allowed to cool naturally in air. Water quenching is entirely avoidable.
Recheck for Porosity by taking a light cut with a 120 grit polish belt or wheel. If pores show up below the skin you need speak to your casting department.
Lastly do add a cathodic and an inhibited alkaline anodic cleaner in sequence after the soak cleaning stage.
After the acid activation the zinc should appear clean whitish signifying good activation. Two rinses are required thereafter.
Add an acid copper step after the cyanide copper stage and plate at least seven and up to 20 microns leveling acid copper for a really excellent finish.
- New Delhi, India
With deep regret we
sadly advise that
Asif passed away
on Jan 24, 2016
I run into delamination problems on my die cast parts once and awhile. Depends on the porosity (not always visually apparent-the casting sometimes seem to have a very thin "skin" on them that covers the voids) of the part. We have had some moderate success buffing the parts before processing. I would go to the root of the problem and try to work with the caster to improve the part quality if possible. If this isn't possible, you may try pre-baking a batch of parts before plating. You are stuck between that old rock and a hard place. Good Luck
March 25, 2012
Q. Please tell me the lead in diecasting, which comes off with the dip in fluoboric acid with the acid dip?
Please tell me if it is before copper plating or after copper plating?
- Ghaziabad, UP, India
March 27, 2012
A. Hi, Abhishek.
Before plating (the last step except rinsing before plating.
Ted Mooney, P.E.
Pine Beach, New Jersey
Blisters in Nickel plating on diecast partsNovember 28, 2017 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread
Q. I am looking for help: my supplier for all the sudden begun making "blisters" in QQ-N-290 over 0.007 mm copper on die cast part Zamak 5.
They were doing fine for over the year and now 60% parts are having blisters.
Blisters are developing on part in time: holding control sample @150 °C for a day will accelerate blister forming.
Supplier is in China, one part having problem, another does not, both plated on same line. We already went through usual suspects: cleaning parts prior to getting them into plating line, tank control etc.
Still one part is almost 100% yield, another 60% scrap, parts are barrel plated.
If anybody willing to share their experience or may suggest what else to look at.
Product designer - Hudson, New Hampshire US
December 1, 2017
Q. Dear sir.
I am Murali from Bangalore INDIA. We made plating on ziplocks which is made from zamak3 fast from few day I absorbing heavy BLISTERING on ziplocks we tried ultrasonic cleaner with surfolin MZ82, surfolin U 25.
Clean with sulfuric acid 10 ml/lit.
(pictures of unplated parts)
Please give suggestion. Thanking you.Murali M
NEW PLATER - Bangalore karnataka INDIA
A. Hi Murali. Diecast parts are a difficult starting point :-(
It looks to me like those parts have not been sufficiently tumbled or vibratory deburred as they appear to have some small scratches or high spots (although pictures are deceiving). But, more importantly, I don't think you'll get them sufficiently clean with ultrasonic cleaning. As a minimum, I think you'll need electrocleaning.
Ted Mooney, P.E. RET
Pine Beach, New Jersey
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